Spray dampening system for offset printing with page control assembly

Abstract

The disclosed system controls, through novel pressure and valving adjustment mechanisms, the application of dampening fluid to the ink roll or offset plate on the plate cylinder of an offset printing press. The dampening fluid passes through a pressure compensator which adjusts the fluid pressure in response to changes in the speed of the press. The fluid at the adjusted pressure is then directed to a spray bar, where it is discharged through a plurality of nozzles. The fluid is directed to the spray bar by a multiple valve, page control assembly. In the page control assembly fluid from a common manifold is discharged through a plurality of dual control valves to respective nozzles. Closure elements for the respective valves are operated by air pistons. A plurality of needle elements for the respective valves are axially adjusted by a common manual control so that adjusting the manual control adjusts the amount of fluid from one segment of the spray bar, preferably corresponding to a full page.

I claim: 
     
       1. In a spray dampening system for delivery of a dampening fluid to a printing press; a plurality of spray nozzles; fluid delivery means for delivering dampening fluid to said nozzles, said fluid delivery means including fluid regulating means comprising a plurality of valves each associated with at least one of said nozzles, each of the said valves including a valve member movable toward and away from its closed position to open and close each valve, each of said valve members carrying a piston, valve operating means for selectively moving each of said valve members toward and away from its closed position, said valve operating means including a resilient member urging each of said valve members toward its closed position and means for selectively directing air under pressure against said valve member pistons to effect movement of said valve member away from their closed position against the resistance of said resillient member, and adjustable valve restriction means for restricting the fluid passage through said valve when said valve is open and selectively movable to adjust the degree of restriction of the fluid passage through said valve, whereby the flow of dampening fluid through each valve to the associated nozzle may be regulated. 
     
     
       2. The apparatus of claim 1 wherein said means for selectively directing air under pressure against said valve member pistons includes at least one manifold in fluid communication with the valve member pistons of several of said valves, and manifold control means for selectively pressurizing said manifold, whereby said several valves may be opened simultaneously. 
     
     
       3. The apparatus of claim 2, wherein there are provided a plurality of manifolds, each in fluid communication with the valve member pistons of a respective set of valves, and said manifold control means includes a separate pressure switch for each manifold. 
     
     
       4. In a spray dampening system having a plurality of spray nozzles and a plurality of valves for controlling the delivery of dampening fluid to respective spray nozzles, each valve providing a variable degree of restriction, the improvement comprising (a) a single control means for manually adjusting in unison all of the adjustable valve elements in the valve for the group of respective adjustment spray nozzles to vary the degree of restriction, each said valve including an inlet orifice in communication with a source of pressurized dampening fluid,   (b) said single control means having a common drive member attached to each of said valve elements for said group of spray nozzles, and further having means to adjust said common drive member for positioning each of said valve elements between a first location of maximum restriction and a second location of minimum restriction,   (c) each adjustable valve element including a shaft having a tapered tip axially introduceable into a respective orifice of said valve,   (d) a separate valve closure member for each of said valves for controlling fluid flow through said valve, each of said closure members being operable by control means independent of said single control means, and   (e) each said valve closure member including a closure element axially slideable upon the shaft of each of said adjustable valve elements for directly opening and closing the orifice of each of said valves in said group independently of the position of said adjustable valve element.   
     
     
       5. The system of claim 4 including common control means for opening and closing all of the valve closure members in said group of valves. 
     
     
       6. The system of claim 4, wherein the valves in said group are arranged in a circular array about a central axis. 
     
     
       7. The system of claim 6, in which the shafts of said adjustable valve elements are parallel to said central axis and each shaft for said group of valves has an end opposite said tip which is attached to said common drive member, and in which said means to adjust the common drive member comprises means for moving the tips of said adjustable elements toward or away from the respective orifices in said group of valves. 
     
     
       8. The system of claim 7, wherein the means for moving the tips includes a screw drive mechanism having a fixed shaft and a rotatable drive fitting threadedly engaging said fixed shaft, said rotatable drive fitting being movable axially along said shaft when said drive fitting is rotated, and means for preventing relative movement between said rotatable drive fitting and said drive member. 
     
     
       9. The system of claim 7, wherein said drive member has means for separately adjusting the axial position of each adjustable valve element. 
     
     
       10. The system of claim 7 in which each valve closure member includes means for advancing and retracting all of the closure elements for the valves in said group simultaneously. 
     
     
       11. The system of claim 10, wherein said means for advancing and retracting the closure elements includes a respective air piston connected to the end of each of the closure elements opposite from the end which engages the orifice of the respective valve; means defining a plurality of respective air cylinders for said pistons;   means for normally urging said closure elements in a direction to maintain the respective orifice in a closed condition; and   means for exhausting the interiors of said air cylinders simultaneously or for pressurizing the interiors of said air cylinders simultaneously to maintain closed or to open the respective valves.   
     
     
       12. The system of claim 11, wherein said means for exhausting or pressurizing includes an air toggle switch and means for communicating the interior of each air cylinder with said toggle switch. 
     
     
       13. The system of claim 11, wherein said air cylinders extend parallel to the central axis and are radially spaced about said central axis.